import json

from django import template
from django.template.context import Context

from .base import InclusionAdminNode

register = template.Library()


def prepopulated_fields_js(context):
    """
    Create a list of prepopulated_fields that should render JavaScript for
    the prepopulated fields for both the admin form and inlines.
    """
    prepopulated_fields = []
    if 'adminform' in context:
        prepopulated_fields.extend(context['adminform'].prepopulated_fields)
    if 'inline_admin_formsets' in context:
        for inline_admin_formset in context['inline_admin_formsets']:
            for inline_admin_form in inline_admin_formset:
                if inline_admin_form.original is None:
                    prepopulated_fields.extend(inline_admin_form.prepopulated_fields)

    prepopulated_fields_json = []
    for field in prepopulated_fields:
        prepopulated_fields_json.append({
            "id": "#%s" % field["field"].auto_id,
            "name": field["field"].name,
            "dependency_ids": ["#%s" % dependency.auto_id for dependency in field["dependencies"]],
            "dependency_list": [dependency.name for dependency in field["dependencies"]],
            "maxLength": field["field"].field.max_length or 50,
            "allowUnicode": getattr(field["field"].field, "allow_unicode", False)
        })

    context.update({
        'prepopulated_fields': prepopulated_fields,
        'prepopulated_fields_json': json.dumps(prepopulated_fields_json),
    })
    return context


@register.tag(name='prepopulated_fields_js')
def prepopulated_fields_js_tag(parser, token):
    return InclusionAdminNode(parser, token, func=prepopulated_fields_js, template_name="prepopulated_fields_js.html")


def submit_row(context):
    """
    Display the row of buttons for delete and save.
    """
    add = context['add']
    change = context['change']
    is_popup = context['is_popup']
    save_as = context['save_as']
    show_save = context.get('show_save', True)
    show_save_and_add_another = context.get('show_save_and_add_another', True)
    show_save_and_continue = context.get('show_save_and_continue', True)
    has_add_permission = context['has_add_permission']
    has_change_permission = context['has_change_permission']
    has_view_permission = context['has_view_permission']
    has_editable_inline_admin_formsets = context['has_editable_inline_admin_formsets']
    can_save = (has_change_permission and change) or (has_add_permission and add) or has_editable_inline_admin_formsets
    can_save_and_add_another = (
        has_add_permission and
        not is_popup and
        (not save_as or add) and
        can_save and
        show_save_and_add_another
    )
    can_save_and_continue = not is_popup and can_save and has_view_permission and show_save_and_continue
    can_change = has_change_permission or has_editable_inline_admin_formsets
    ctx = Context(context)
    ctx.update({
        'can_change': can_change,
        'show_delete_link': (
            not is_popup and context['has_delete_permission'] and
            change and context.get('show_delete', True)
        ),
        'show_save_as_new': not is_popup and has_change_permission and change and save_as,
        'show_save_and_add_another': can_save_and_add_another,
        'show_save_and_continue': can_save_and_continue,
        'show_save': show_save and can_save,
        'show_close': not(show_save and can_save)
    })
    return ctx


@register.tag(name='submit_row')
def submit_row_tag(parser, token):
    return InclusionAdminNode(parser, token, func=submit_row, template_name='submit_line.html')


@register.tag(name='change_form_object_tools')
def change_form_object_tools_tag(parser, token):
    """Display the row of change form object tools."""
    return InclusionAdminNode(
        parser, token,
        func=lambda context: context,
        template_name='change_form_object_tools.html',
    )


@register.filter
def cell_count(inline_admin_form):
    """Return the number of cells used in a tabular inline."""
    count = 1  # Hidden cell with hidden 'id' field
    for fieldset in inline_admin_form:
        # Count all visible fields.
        for line in fieldset:
            for field in line:
                if not field.field.is_hidden:
                    count += 1
    if inline_admin_form.formset.can_delete:
        # Delete checkbox
        count += 1
    return count
